The new eastern span of the Bay Bridge suffers from a lack of quality control that calls into question the bridge's long-term health, a panel of engineers said Thursday.

Findings that at least some of the bridge's rods and bolts are excessively vulnerable to corrosion, along with the discovery that some of the span's tendons have become corroded, "may not compromise the bridge's safety at the moment," the six-member panel said in a report to the state Senate Transportation and Housing committee.

But "there could potentially be an increase in the scope and expense involved in maintaining the bridge," the engineers said.

The problems that have arisen on the $6.4 billion bridge are "sufficiently basic" that the only explanation for how they were missed was that no one was looking, said the panel, chaired by Georgia Tech engineering Professor Reginald DesRoches.

"Based on our discussions with the project team on various issues, the implementation of the construction quality assurance has been deficient in some critical areas," the engineers said. The problems, the panel found, may indicate "an underlying problem of inspection vigilance of the field staff."

State Sen. Mark DeSaulnier, chairman of the transportation committee, called the report "a public indictment of Caltrans" and said it raised questions about how much taxpayers and toll payers will have to pump into maintenance of the new eastern span.

"We know it came 10 years late. We know it cost $5 billion more than expected," he said. "How much more will we incur in maintenance costs?"

Caltrans Director Malcolm Dougherty said the engineers' conclusions were consistent with the department's own evaluation.

"That is that the bridge is safe," he said.

Dougherty said the agency planned to talk further with the engineers about their concerns with Caltrans' quality assurance procedures.

"We want to make sure we follow up with them so we can add those to our lessons learned," he said.

The engineers found that the cracking risk to galvanized rods and bolts, like the 32 fasteners that failed on the span last year, has long been recognized, and that Caltrans could easily have used a different type of high-strength steel more resistant to attack by corrosion-causing hydrogen.

The panel questioned why Caltrans accepted the first batch of rods in 2008 that ultimately failed, even though they had failed a basic quality test, and why work crews had left them exposed to standing water.

"Many factors potentially contributed to the bolt failure," the panel found, including design choices and "inadequate quality control and quality assurance" during construction.

The panel warned that some 2,000 remaining rods and bolts "cannot be considered immune" from failure over the life of the bridge. Caltrans is conducting tests to determine whether other fasteners are at risk.

The engineering panel also faulted Caltrans for not protecting the high-strength steel tendons used on the skyway portion of the bridge from being exposed to water for months during construction. The tendons were installed inside ducts in the concrete and water seeped in over time, causing them to rust.

The engineers recommended that Caltrans do more to assess the chance that those tendons could suffer from more extensive corrosion. Caltrans says it has minimized the chance that happened.

The engineers also suggested that the bridge's main cable might be at risk of corrosion like the rods and bolts, especially in "less protected parts of the cable." They recommended that the bridge officials consider a "full cable dehumidification as a future enhancement" on the span.

In addition to the quality control steps, the engineers said Caltrans should perform a rigorous risk analysis to see how the span might perform in a major earthquake. Such analyses are commonly done for major structures such as nuclear power plants and offshore oil platforms, the panel said.